by Robert Connell Clarke
Gross Phenotypes of Cannabis Strains
The gross phenotype or general growth form is determined by size, root production, branching pattern, sex, maturation, and floral characteristics. Most imported varieties have characteristic gross phenotypes although there tend to be occasional rare examples of almost every phenotype in nearly every variety. This indicates the complexity of genetic control determining gross phenotype. Hybrid crosses between imported pure varieties were the beginning of nearly every domestic strain of Cannabis.
In hybrid crosses, some dominant characteristics from each parental variety are exhibited in various combinations by the F1 offspring. Nearly all of the offspring will resemble both parents and very few will resemble only one parent. This sounds like it is saying a lot, but this F1 hybrid generation is far from true-breeding and the subsequent F2 generation will exhibit great variation, tending to look more like one or the other of the original imported parental varieties, and will also exhibit recessive traits not apparent in either of the original parents. If the F1 offspring are desirable plants it will be difficult to continue the hybrid traits in subsequent generations. Enough of the original F1 hybrid seeds are produced so they may be used year after year to produce uniform crops of desirable plants.